The present invention relates to a method for rinse treatment of a substrate or, more particularly, relates to a method, in the manufacturing process of various semiconductor devices, for rinse treatment of a substrate from which the patterned resist layer has been removed by using a remover solution following a photolithographic etching treatment with the patterned resist layer as a mask, using a specific solvent as the rinse liquid not only having excellent effect of rinse but also free from disadvantages in the toxicity to human bodies, environmental pollution in connection with waste disposal and danger of fire.
As is known, the manufacturing process of semiconductor devices such as ICs, LSIs and the like is typically performed in a series of steps including: formation of a thin oxide film on the surface of a substrate such as a semiconductor silicon wafer; formation of a photosensitive layer by uniformly coating the substrate surface with a photoresist composition; formation of a patterned resist layer by pattern-wise exposure of the photoresist layer to light followed by a development treatment; etching treatment of the underlying oxide film pattern-wise with the patterned photoresist layer as a mask; and complete removal of the photoresist layer from the substrate surface.
The removal of the patterned photoresist layer in the last mentioned step is usually performed by using a remover solution which is an aqueous solution of an inorganic acid or base or an organic solvent capable of dissolving the photoresist layer. Among these conventional remover solutions, organic solvents are usually preferred because danger to workers is involved in the use of an inorganic acid or base as the effective ingredient of the remover solutions. Exemplary of the organic solvents conventionally used as a remover of the patterned photoresist layer are alkylbenzene sulfonic acids, mixtures of an aromatic hydrocarbon solvent and an alkylbenzene sulfonic acid and the like.
It is of course that, when the patterned photoresist layer has been dissolved away by using an organic solvent as the remover, the substrate surface must be completely freed from the remover. Since the remover on the substrate surface more or less contains the photoresist composition dissolved therein, the substrate from which the patterned resist layer has been removed away by using an organic solvent cannot be directly transferred to a rinse treatment with water in order to avoid precipitation of the photoresist composition in the remover solvent admixed with water to be deposited again on to the substrate surface. Therefore, it is essential that the substrate from which the patterned photoresist layer has been removed by using an organic solvent as the remover should be rinsed, prior to rinse with water, with an organic solvent.
Conventional organic solvents used for the rinse treatment include trichloroethylene, methyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone and the like.
Although these organic solvents are indeed effective as a rinse solvent to remove the remover from the substrate surface, they are not free from various disadvantages and problems. For example, trichloroethylene and other halogenated hydrocarbon solvents are disadvantageous in respect of the toxicity to human body and the problem of environmental pollution as are the very serious issues in recent years. Other solvents are also not free from several disadvantages since they are usually inflammable with a relatively low flash point to cause problems in the danger of fire and storage. They are sometimes responsible for the contamination of working environments as a result of their relatively large velocity of vaporization. While trichloroethylene is useful as a rinse solvent for negative-working rubber-based photoresist compositions, it cannot be used for positive-working novolac-based photoresist compositions, for which organic solvents other than trichloroethylene must be used. Accordingly, the rinse solvent must be replaced with another when the working type of the photoresist composition under treatment is changed from negative- to positive-working or vice versa to cause a great decrease in the working efficiency.